


The Undying

by CrushingOnSans



Category: Undertale (Video Game)
Genre: Alphyne, Alphys is kinda OC sorry, Death, F/F, M/M, Papyrus Shenanigans, Papyrus scarf, Sans Is A Dick, Suicide mention, This is going to be sad just warning you, history of gaster, royal guard, scarf
Language: English
Status: Completed
Published: 2016-11-21
Updated: 2016-12-11
Packaged: 2018-09-01 05:18:29
Rating: Mature
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 4
Words: 13,586
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8610283
Author URL: https://archiveofourown.org/users/CrushingOnSans/pseuds/CrushingOnSans
Summary: Something is killing it's way through the Underground, and Undyne is powerless to stop her friends from being hurt.There's just not enough Undyne multiverse fanfiction out there. So HERE YOU GOOOOOOOOOOI will add tags for characters as they enter the story, but the archive warnings and relationships that are currently listed will be the only ones listed through the whole story.   Abandoned





	1. Path of Destruction

**Summary for the Chapter:**

> Wow, look at me, starting another fanfiction, that's what I need
> 
> Warnings:Suicide mention, drug use, alcohol use, Sans is kind of an asshole

“EXCUSE ME?!?” shouted Undyne at the little skeleton standing before her. He was looking her right in the eye, a lazy smile plastered on his face, hands shoved in his blue hoodie’s pockets. He was swaying slightly, and his white eyelights were hazy. 

“I said…” he stopped for a second, seemingly having forgotten what he was going to say. Undyne growled in frustration. The fucker was either blazed or wasted, but either way he seemed basically useless. How he managed to keep Papyrus from noticing when he was like this, she would never understand. Although it probably helped that plastered Sans wasn’t an altogether different person than sober Sans. Less angry, maybe. Definitely less controlled. 

He finally seemed to remember how a brain worked. “I said that it doesn’t really matter. Don’t worry about it.”

Undyne just stared at him for a moment. “I tell you that something is carving a fucking path of death through the Underground and your response is to tell me ‘Don’t worry about it?’”

He just stared at her for another moment before he gave half a shrug and said, “Yeah, pretty much. It doesn’t matter.”

Undyne glared at him. “Monsters are dying, Sans, and your  _ job _ is to look into this shit! How doesn’t that matter?” She was getting louder, almost screaming at him. She looked at this sorry excuse for a monster standing in front of her, not even having the decency to look nervous at her obvious rage, and did her best to stop herself from losing what cool she had left. Occupied thus, it took her a moment to realize that he was actually laughing.

“What the hell are you laughing at?” she yelled. 

“Monsters are dying, Sans!” he mocked in a high-pitched rendition of her voice. “Monsters are dying, and you have to help us! Oh, please help us, oh powerful one, we just know you can do it!”

She just stared at him. She had never seen him talk like this before. Mocking was basically the only way he knew how to talk, but this was bordering on hysteria. He kept going in that mocking tone, repeating himself and he and what sounded like Papyrus until she finally shouted “STOP!!!”

He fell silent, swaying again and glaring at her. His easy confident was gone, the smile had fallen from his face. 

“Is that what this is about, you useless asshole?” She was still shouting and she didn’t know how to stop. “‘It doesn’t matter’, ‘you have to help us’” She repeated his words, not bothering to be mocking of his deeper tones. She felt the last of her control snap and she said “You killed some human children for the greater fucking good of the entirety of monsterkind and it’s  _ just now _ getting to you?

She regretted it the moment it came out of her mouth, especially when she felt his magic flare up and saw his eyelights disappear. She had only seen him this angry a couple of times, and it had always been something to behold. Not that she was scared. She reserved that right for things that could actually kill her. 

Okay, maybe she was a little scared. 

“You don’t know what the hell you’re talking about” he growled. She could feel his magic flaring, could see it sparking in his hands. He seemed to be trying to rein himself in, and she was one of maybe a handful of people who know exactly what sort of state she would be in if he couldn’t. 

And yet she couldn’t seem to make herself stop. “You need to stop wallowing in self-pity and  _ do your fucking job _ !” she yelled. 

Somewhat to her surprise, Sans didn’t immediately turn her into a smoking pile of dust. Instead, he just looked at her for a moment before he extinguished his magic. He walked over to the door, wrenching it open and standing aside. His next words were dangerously quiet. “Get the hell out of my house”

Undyne threw her hands up in the air and stomped out the door. She heard it slam behind her as she made her way angrily down the streets of Snowdin.

X-X-X-X

Almost 20 years ago, the Royal Labs were nothing short of a place of miracles. Monsters that went through the doors seemingly broken beyond repair same back out better than they had been before, and all of it was overseen by the esteemed Royal Scientist, Dr. WingDing Gaster. 

Having come from a family of Royal Guardsmen and war heroes, it came as somewhat of a surprise to those in the Gaster family’s social circles that their son showed so much promise in the field of science. From the moment he started his apprenticeship, his sharp wit and quick mind seemed to start a transformation throughout the entire field.

W.D. Gaster, as he quickly became known, moved incredibly quickly through the ranks, and before anyone really seemed to know what was happening, he was the new Royal Scientist, personally selected by King Asgore himself. With his new power came a new era of scientific advancement. Through the stories of the miracles being performed but this young genius and those around him, the Underground felt itself come together, felt itself start to  _ hope _ again.

Especially one it became known that he may have come up with a way to rescue them from their buried prison. No one doubted his capability, and expectations were high. 

Soon after this became known, Gaster had a son. No one really questioned where he came from. After all, Gaster was young and handsome and very much sought after. He was unmarried, yes, but he had no end of potential mates. The child was just as smart and witty as his father, and he had the added bonus of being adorable as hell. Everywhere the kid went, he attracted and distracted, which may have been why Gaster stopped bringing him along to the labs. The new father seemed happier to no end, growing in excitement and skill even as the child grew. 

Sadly, this air of happiness and unity could not last. Years passed, and the miracles continued, but no apparent progress was made in the effort to free monsterkind. Even the happiness Gaster seemed to have found in his child seemed to have disappeared, replaced with reports of apparent disappointment and anger. When the child was about 6, Gaster appeared, again, with a child. Unlike with the first, this son only seemed to increase Gaster’s despondency. He began to stay more and more at the labs, leaving his sons at home (hopefully with someone watching over them. No one ever really asked). Over the next few years, Gaster seemed to fade more and more, withdrawing into himself and his all-consuming projects, ignoring the day-to-day goings on of the rest of the labs. And thus began the end of the age of miracles. 

The final straw came on the day that Gaster’s 9-year-old son found him in his bedroom, turning to dust around the knife that the former genius had stabbed through his own soul. 

Before his funeral had even been organized, Gaster’s top assistant, Alphys, was appointed as the new Royal Scientist. The crown’s apparent attempt to preserve the good name of that title failed miserably, Gaster’s sons were nowhere to be found, and along with them, all of Gaster’s research into destroying the barrier had also disappeared. The Royal Labs basically fell into ruin as scientist after scientist left the employment of the crown in favor of positions not associated with so much tragedy. 

Less than two years after this, the Royal family suffered their own great loss, and all eyes finally turned away from Alphys, along with any remaining support she’s had from the crown. And so, being as painfully shy and non-confrontational as she was, she seemed to accept her fate. 

15 years late, here she was again, appearing to accept the inevitable. She sat at her desk, nodding absently along to the tirade happening behind her as she typed up an old report she had found inside a stack of dusty boxes. 

“Who does he even think he is?” Undyne was saying. “I mean, I know he works at a hot dog stand but does he have to be such a  _ dick _ ? And that’s not exactly his most important job! Does he even realize what he’s letting happen? Monsters are  _ dying _ , Alph! I know I’m captain of the guard, and believe me, if I could do it I would, but only the Royal Judge is allowed to deal with humans! So if it’s a human, I can’t do a damn thing about them! That lazy dickbag needs to...needs to…” She stopped, groaning, and plopped down in a chair next to the nervous little yellow dinosaur. “What should I do, Alph?” she asked, burying her face in her hands. 

No response. Undyne looked up to see Alphys nodding along distractedly and typing. “Alphys!” she said, a bit louder than she’d meant to. 

Alphys jumped, nearly falling out of her chair. She turned to face Undyne. “S-sorry!” she stuttered. “He’s a really big j-jerk!” she nodded, harder now, as if to punctuate her statement. 

Undyne sighed quietly. “What are you working on?” she asked, knowing she wasn’t going to get very good advice while the other was in the zone. 

Alphys smiled a little bit, turning back to her computer. “I found this b-big stack of boxes in the t-true labs. They h-had all these reports in them, from w-when G-gaster was still here! There’s a lot of p-promise here!” She certainly seemed excited. 

Undyne leaned closer to the computer. Her forehead crinkled slightly as she tried to decipher what Alphys had already typed. “What does ‘timeline theory’ have to do with escaping this glorified cave?” she asked. 

Alphys ducked her head slightly. She hands gripped each other tightly and she started to sweat. Undyne frowned again and leaned back in her chair. She had known Alphys for almost 10 years now, and they had been almost like sisters for a large portion of that, so she knew with an absolute certainty that whatever Alphys said next would be a lie. 

Fortunately for the slightly shaking scientist, Undyne’s phone chose that moment to ring. She gave Alphys one last questioning look before she accepted the call and lifted it to her ear. “Hello?”

“UNDYNE!” the reedy voice on the other end was loud enough to make her wince, but then she smiled. “Papyrus!” she bellowed back. She saw Alphys wince slightly at the volume change, so she stood and moved away slightly so that Alphys could have some small amount of peace. She could hear the clacking of her resumed typing as Papyrus continued. 

“NYEH HEH HEH! THE GREAT PAPYRUS HAS FOUND EVIDENCE FROM THE CULPRITS! FOOTPRINTS ALL AROUND THE NORTHERN ABANDONED AREAS OF SNOWDIN FOREST!” he was clearly beyond excited at having found something that, in his mind, was amazing evidence. 

Despite the fact that this really was good information, Undyne sighed slightly and passed a hand over her eyes. “Papyrus, why are you in Snowdin forest? And how did you even know about what’s been going on?”

Papyrus paused for a moment. “THE GREAT PAPYRUS DID NOT BRIBE DOGGO FOR IDEAS OF HOW TO HELP THE GREAT ROYAL GUARD, IF THAT IS WHAT YOU ARE THINKING! AND I WAS IN SNOWDIN FOREST LOOKING FOR CLUES, OF COURSE!”

Undyne snorted quietly. She was going to kill Doggo the next time she saw him. “Thank you Papyrus. Alright, I’ll be there soon okay? Stay where you are” He shouted his goodbyes and hung up before she had a chance to respond.

Undyne shook her head and turned to Alphys just as there was a loud crash. Undyne took half a step forward to help before she realized the little dinosaur had just knocked over a chair when she stood up too fast. Undyne paused when she saw the look on her friend’s face. 

She was clutching the report she had been transcribing so tightly she was creasing the paper. She looked completely shell-shocked. As Undyne watched, Alphys’s hands began to shake and a huge smile spread across her face. 

“Alph? You okay?” asked Undyne, stepping towards her hesitantly. Alphys looked up, but seemed to be staring right through her, excitement beginning to make her entire body shake. “Y-yeah! I’m f-fine!” she grabbed her phone and started dialing a number as Undyne said “Okay...Well I have to go meet Papyrus, he said he found something to help find the person who’s been killing all those monsters…”

Alphys just nodded, waving goodbye as she held the phone to the side of her face. As Undyne left the labs, she heard Alphys squeak “Y-you n-need to get over h-here! N-now!”

X-X-X-X

Papyrus was standing in the middle of a clearing at attention when Undyne arrived at Snowdin forest. He was wearing his homemade version of a Royal Guard’s uniform that she had never seen him out of, complete with his strangely tiny blue shorts and the red boots, gloves, and scarf. Said scarf was flapping slightly, despite there being no wind. Undyne could see the slight glow of orange that signalled he was using his magic in an attempt to to look cooler. He must be really proud of himself. She sighed quietly. Despite the fact that the northern part of snowdin forest  _ was _ abandoned, it really wasn’t all that unusual to see footprints out here. It was still worth checking out, but she definitely wouldn’t have come out here personally if the report had come in from anyone other than Papyrus.

He heard her coming up behind him and turned on his heel in a way that was probably supposed to look military, but just ended up wit his nearly tripping over his own feet and falling flat on he face. “CAPTAIN!” he recovered quickly and saluted pristinely. 

Undyne laughed. “You know you don’t have to be so formal Paps! We’re cool! And I’m not your captain yet!”

He frowned slightly at the reminder that he wasn’t yet a part of the Royal Guard, but his usual smile quickly took back his face. “ALLOW ME TO ESCORT YOU TO THE EVIDENCE!” he exclaimed before beginning to walk in that paradey way of his in the apparent direction of the “evidence”. 

Undyne followed, feeling herself walking a little taller than usual. Papyrus had that effect on people. He was just so happy all the time, he just made you want to be happy too. His unending confidence, instead of being straight-up narcissism, just made you feel like you might be as cool as he obviously thought he was. How a guy like this had a brother like Sans, Undyne didn’t even pretend to understand. 

She growled under her breath at the thought of that little cretin, but was quickly distracted by Papyrus coming to an abrupt stop directly in front of her and throwing his arms out to the side with a flourish, causing Undyne to have to dodge first Papyrus, then his swinging arms. “WE HAVE ARRIVED!” he announced. 

“You don’t say!” he exclaimed, grinning. She looked at the ground where he was gesturing, then she frowned and kneeled to have a closer look. 

There weren’t just a few footprints, there were  _ tons _ . It looked as though there was some kind of a large party that had passed through here recently. She could see the footprints of probably over 80 or so monsters, all seeming to converge in this area after wandering from all different directions.

There was one set of prints that appeared more than any other, readily apparent from the fact that they appeared to be from a pair of high-heeled boots. This set was everywhere, accompanying several of the other trails and seeming to circle this area in particular. She stood quickly, turning to Papyrus. 

“Where do these trails come from?” she barked. She knew that she sounded far more authoritative than she normally did when speaking to Papyrus, but this had just become serious. If these led to who was responsible, it would mean that the threat wasn’t likely to be human, which meant that she wouldn’t need to get help from that useless sack of bones after all.

Papyrus straightened back up into attention and saluted again. “CAPTAIN! I ONLY WAS ABLE TO BACKTRACK A FEW OF THESE TRAILS BEFORE YOU COMMANDED ME TO STAY WHERE I WAS, BUT THEY ALL SEEM TO COME FROM NOWHERE AT ALL!” 

Undyne stared at the skeleton for a moment. Well this might be a whole new level of nonsense. “What?”

“THEY APPEAR OUT OF NOWHERE, CAPTAIN! THEY JUST BEGIN RANDOMLY AND THEN THEY COME HERE, WHICH APPEARS TO BE SOME KIND OF GATHERING PLACE, BEFORE CONTINUING ON ALONG THAT PATH!” Papyrus said in his best Royal Guard voice, pointing to a deeper path that Undyne had not previously noticed on the opposite side of the clearing. 

“Where does that path go?”

“I HAVE NOT HAD THE CHANCE TO FOLLOW IT, CAPTAIN”

“Well come on then!” Undyne started walking across the flattened area of snow. She heard Papyrus trailing along after her. 

They followed the path in silence for a while, Undyne carefully studying her surroundings while Papyrus watched the path in front of him. There didn’t appear to be any disturbances among the trees, but that didn’t mean much. The path didn’t show any signs of stopping, so it was likely that there were no monsters at this point. 

After a few minutes of walking, Papyrus came to a sudden stop. Undyne turned to look at him questioningly and he pointed silently. Papyrus was never silent, so she knew it was something serious. She walked back to where he was and followed his line of sight. There was something moving. It wasn’t on the path, but that didn’t mean the path wasn’t a diversion or an ambush. She cursed herself for not thinking of that earlier. “Stay here, Do Not Move” she whispered. Papyrus nodded and planted his feet at attention. Undyne quietly made her way towards the motion. Peeking through the trees carefully, she realized it was just a pair of teenage Snowdrakes. She sighed in a combination of relief and disappointment as she stepped out from the trees. 

“You need to get home to your parents. This area of the woods is not safe.” She said in her most authority-filled voice. 

The Snowdrakes jumped at her appearance, then nearly ran to obey her. She grinned after them, pleased at the effect she had had. Then she turned to go back to the path. It was only a moment before she realized that she could no longer see Papyrus. She frowned. He was usually so good at following orders.

She had never met anyone quite so determined to reach perfection as Papyrus. When he had decided that he wanted to join the Royal Guard, he had sat on her front step for three straight days until she agreed to train him. Secretly, she thought he would be unlikely to make it into the guard. He was just too kind. In any other situation, it would make him excel, and it truly made him into the best kind of person. But a Royal Guard that was as kind and full of mercy as Papyrus was likely to be ripped into smiling pieces. 

Undyne was snapped out of her reverie by a loud scream of terror.

She froze for a split second.

Another scream.

That was Papyrus’s voice.

She started to sprint in the direction of the sounds. 

“UNDYNE!!!”


	2. Grief

**Summary for the Chapter:**

> Sorry this took me so long, guys. I knew what I needed to have happen in this chapter and I just couldn't get it to come out in actual story form. I'm fairly sure this is still complete crap, but here, take the stupid thing anyway lol. 
> 
> Warnings:Major Character Death, dealing with death.

“And it was just written on a sheet of paper in a box this whole time?”

The dim light of the upper floors of the Royal Labs cast long shadows over its two inhabitants. Their features were almost impossible to make out, but the first speaker was pacing nervously, gripping a sheet of paper almost tightly enough to tear it. The second occupant was wringing their hands nervously, and when they spoke up, they were quiet.

“Yes, I found the b-box just yesterday in one of t-the broken f-filing c-cabinets and I brought it up here to t-transcribe, and I just...I c-couldn’t believe it w-when I s-saw it”

The first speaker stopped pacing and turned almost too quickly to face the other.

“Well? Where is this device?”

“I’ve g-got it right here. But S-Sans, wait! You can’t use it!”

“Why the hell not?”

“G-Gaster said in his n-notes that he wouldn’t be able to use it b-because his b-body density wasn’t--”

“I can’t use it because I’m a skeleton? Seriously?”

“Unfortunately, y-yes”

Sans threw his hands up in the air and resumed his pacing.

“Well, shit. What the hell are we going to do about this then? I’m not about to just give something like this up just because my fuckin’  _ body density _ isn’t high enough! Hell, Alph, this is the closest we’ve ever come to finding a solution to this!”

“I...I c-could use it”

There was a long pause.

“...Are you sure? Will you be able to take it? You barely survived Gaster implanting the memory modifier, how will you take this?”

“B-better than you, at l-least”

“I guess so. Well, how does it work?”

“Come on, I’ll s-show you. Maybe we have some t-time for t-testing but if n-not, that’s okay”

There was a short laugh before Alphys continued.

“It’s n-not like I w-won’t come b-back n-next time, r-right?”

“Alph, I’m sorry, you know I wouldn’t--”

Sans was cut off by a loud noise from the large monitor on the other side of the labs. 

“UNDYNE!!!”

He froze in his pacing and stared in the direction of the screens. He took half a step towards them before Alphys put a hand on his arm. 

“S-Sans. Don’t. Y-you don’t have to w-watch it every time. If t-this works, y-you’ll never h-have to watch it again”

There were more screams coming from the monitor, and Sans looked in that direction for a moment before turning to Alphys. 

“Yeah. Yeah, okay. Show me how the thing works, let’s go”

They got into the elevator that led to the True Labs and the doors closed behind them, so that they couldn’t hear when the screaming stopped and Undyne’s voice filled the empty lab instead. 

“Oh, God, Papyrus, no...nonono, Papyrus, goddamnit, no!”

X-X-X-X

Undyne stood in front of the doors to the lab, a soft red scarf clutched tightly in her hands. She had raised her hand to knock and found herself completely unable to. She was just so numb. 

She wasn’t sure exactly how long she’d searched the forest after finding Papyrus’s dust, but she had found nothing. There was only the same paths, cropping up all over the forest and all leading to the same place, then joining into that single path. The path they had been following ended up circling back into itself. Useless. 

She gripped the scarf more tightly in her hands and brought it up close to her face. She couldn’t seem to cry anymore, she couldn’t seem to feel much of anything anymore. He was just gone. Just like that. She would never hear his overbearing voice, watch him parade around the forest, tell him he was cool. 

Why had she left him alone?

The scarf smelled like several different MTT products mixed with a scent that she knew was from his magic residue. It was a scent so uniquely  _ Papyrus _ that she found herself just breathing it in and wishing very hard that she could hug him.

Papyrus had been her best friend. What was she going to do without him?

And how was she going to tell Sans?

When she finally gave up on finding whatever had killed her friend, she had gone to the brother's house, only to find it empty. She had stood there on the front step, completely unsure about what to do. Despite her somewhat intense dislike for the asshole, he had been the only person who loved Papyrus more than she did. He deserved to know before anyone else. But after standing on their front step for almost half an hour without him coming home, she had been unable to take it anymore. She needed Alphys. 

And so here she stood, in front of Alphys’s front door, so far gone that tears were unable to come, and Undyne was unable to knock. 

She couldn’t talk about this, the worst failure she had ever had. This was her fault, wasn’t it? She had let him come with her, she had left him alone, she had raised his hopes despite the fact that she knew,  _ she knew _ that he would never be able to make it in the Royal Guard. He had died believing her lie. And now, he would never hear the truth. 

But she couldn’t do this without Alphys. 

So she knocked. 

The door slid open smoothly, as it always did. Undyne steeled herself before stepping through, lowering Papyrus’s scarf from her face, but still holding onto it tightly. The lights were turned down very low, so that she couldn’t see a whole lot of anything. She looked around, almost confused, but not quite capable of something as complicated as confusion. Then the lights came on, far too brightly and far too suddenly, and Undyne threw her arm over her eyes. 

She heard the skittering of Alphys crossing the room much more quickly than she usually did, and Undyne lowered her arm just in time to see Alphys stop directly in front of her, looking up at her with far more sadness than Undyne felt capable of understanding at the moment. 

“Oh, Undyne. I’m so sorry” Alphys’s voice was completely devoid of a stutter for once, and she wrapped her arms around Undyne’s waist, giving her a hug as best she could considering their height difference. 

Then Undyne was crying, and she fell to her knees, hanging her head and finally letting her emotions out. She sobbed as Alphys hugged her properly, whispering reassurances that it wasn’t her fault, it wasn’t her fault. Undyne had no idea how Alphys knew what she was feeling, how much she was blaming herself, but she let herself accept the comfort without question for now. 

“Alphys, I l-left him alone. I left him alone, h-how could I be so s-stupid?”

“Undyne, it w-wasn’t your fault”

“It w-was! Alph, he was my best friend! I l-let him get killed!”

“It’s okay, it’s all going to b-be okay, it wasn’t your f-fault”

Her tears had ended, but she still shook. “What am I going to do without him, Alph? He was...he was so irreplacable”

“I know, Undyne, I k-know”

“How could I have been so stupid?”

There was a tug on the scarf that she was still holding tightly, and she wrenched it out of the hands of the other person, holding it close to herself and looking up. 

Sans was standing beside them, one hand partially outstretched to where the scarf was. He was looking at the spot where it had just been with a look like he didn’t understand why it had been taken away, and then he lifted his gaze to hers. 

For a moment, she saw something in his expression that matched her own grief. For a moment, she saw how much he loved Papyrus, how much this hurt him. For a moment, she couldn’t hate him. She just couldn’t make herself. 

Then his face closed up, and his eyes lidded. “Keep it” he said quietly, his voice betraying none of the raw emotion she had seen only a moment before. Then he turned and went to the elevator that she knew led down to the rest of the labs. 

She felt herself get angry, and she let it set a fire inside her because angry was easy, it was so much simpler than the emptiness that had threatened to eat her away only a moment before. She pulled herself out of Alphys’s arms and stood, crossing to Sans in a few steps. 

“That’s it? ‘Keep it’?” she growled.

He didn’t even look at her. “Yeah, Undyne. Keep it. I don’t care”

“ _ You don’t care? _ How could you possibly not care? He was your brother!”

He looked at her then, his eyes still lidded, still empty of any sort of grief. 

“Didn’t you even love him?” she found herself saying. 

He didn’t say anything for a moment. He just looked her in the face, avoiding her eyes. She almost saw a flicker of something in his eyes, just for a split second, but it was gone before she could even be sure it had really been there. “Yeah” he said, his voice flat. “I guess I did. Do. I do” his eyes dropped again, and he shoved his hands further into his pockets. “It just doesn’t matter”

Undyne growled and stepped forward, into his personal space. “YES, YOU LAZY FUCK! YES IT DOES!” then her voice broke. “Of course it matters”

She felt Alphys tug on her hand, and allowed herself to be pulled back and away from Sans, who still wasn’t looking at her. 

“Oh, fuck you, Sans. Just fuck you! I’m going to find whoever killed him, and I am going to fucking destroy them, and you can just sit here on your lazy ass and not care” she yelled, pulling her arm out of Alphys’s grip roughly and whirling around.

“N-no, wait!” said Alphys as she started to storm off. 

“You can’t go after them” Sans said from behind her.

She spun back around quickly and yelled “Oh, I’m sorry, I thought it didn’t matter!”

“You can’t go out there”

“Why the hell not?”

“Why can’t you just listen to us?”

“Are you  _ kidding _ me? You’re a--”

“U-Undyne!” Alphys said, more firmly than Undyne had ever heard her. “Stop!” 

“But he’s--”

“No, Undyne! W-we need you t-to stay here!” 

Undyne looked down at her. She was taking  _ his _ side? 

“No. No, I’m going, I’m going to kill the person that took my best friend from me!” she said, very calmly. Then she turned around and started to walk towards the door. 

“Sans! No!” She heard Alphys say, and she turned back part of the way before she felt pain bloom across her skull and blackness overtook her vision.

X-X-X-X

When Undyne woke up, she couldn’t help but groan loudly. Her head hurt like hell. She went to rub at her eyes, but she couldn’t get her arms to move. 

Her head cleared a bit, and she realized that her arms were tied behind her back. Her eyes flew open and she tugged harder at her bonds, panicking slightly. The last thing she remembered…

Oh, that  _ bastard _ . 

He was standing in front of her, eyes glued to the monitor, seemingly oblivious to her struggles. She was tied up sitting down, her ankles bound to the legs of the chair and her arms rendered immobile behind her. She started to struggle quietly against the rope tying her arms. She twisted herself, attempting to work free, but it just made her wrists hurt.

“That’s not going to work” came San’s voice. 

She stopped struggling to glare at his back. “Screw you” she spat.

“No, thanks. I’m not particularly interested, and I’m fairly sure that you have a girlfriend, so…” 

He glanced back to grin at her, like he was funny or something. She just kept glaring at him. 

“So you’ve got me tied up here. What’s going to happen next?” she asked as nonchalantly as she could. 

“I thought we already went over this? You might want to stop coming on to me, there, kiddo” 

“Oh, shut the hell up”

“Nah, I’m just kidding. Come on to me all you want”

“What the hell is wrong with you?”

At that, he gave a short laugh, then lapsed into silence. When she didn’t receive a response, she went back to struggling against her ropes. She was  _ so close _ …

“You really don’t have any way to understand this, you know. You...you live your life, and you don’t even have any idea what’s happening” 

She looked up at his back in disgust. She could care less about his shitty backstory, she was still going to strangle him when she got out of this chair.

“You have no idea what it’s like to live the same thing, over and over and  _ over _ again, and you can’t do a goddamned thing about it. People keep dying, and it’s supposed to be your job to protect them and no matter what you try, no matter how soon you find them, you  _ always fucking fail _ . You always end up with that goddamned scarf around your neck, facing off against your brother’s murderer, but hey, they have all the time in the world, they can try again and again, and no matter what you do, no matter what you try, they always kill you”

Undyne could care less what he was saying, but at the mention of the scarf, she realized it had been wound around her own neck. She managed to get her right hand out of her bonds, and her left hand quickly followed. As quietly as she could, she leaned forward to untie her ankles. 

“And then they just start it all over again! Every time! And i thought...I thought I was the only one who remembered for a very long time, but...apparently not” he continued, still staring at the monitor. 

Her ankles free, Undyne stood up very slowly and began making her way across the room towards Sans. Just a few more steps…

Suddenly, he swung around and grabbed her by the wrists, twisting them in such a way that she was held trapped by her own arms, his shorter stature no longer an issue as he forced her down onto her knees and held her there. “How stupid do you think I am?” he asked angrily. “You're the captain of the guard, I'm pretty sure ropes and a chair wouldn't hold you for long”

When her struggling did nothing to dislodge his hold, she growled and asked “Where the hell is Alphys? She's really okay with this bullshit?”

He laughed shortly. “She knows you well enough to agree that it's necessary to keep you here until she's done her part. And as for where she is, haven't you been watching the screen?”

Undyne looked at the monitor, which she now realized was displaying Alphys, walking through the same part of the forest that Papyrus…

“What the hell is she doing out there? She can't protect herself!”

“She's not an idiot, she took Mettaton with her” he retorted, then his face fell. “But I agree. I'd give just about anything to be in her place. But there's some bullshit about body density…”

Undyne tuned him out. On the screen, Alphys was walking very determinedly, fiddling occasionally with something she held in her hands and changing direction slightly. “What the hell are you doing, Alphys?” she asked under her breath. 

“She's stopping the cycle. That machine there is going to fix everything”

Undyne ignored him and kept watching. Alphys had stopped now, and she was looking down at the little machine in confusion. She messed with a few buttons, but nothing seemed to change. Then, suddenly, Mettaton’s screams were echoing through the room. Alphys's head shot up at the same moment that Sans's grip loosened slightly in surprise. Undyne was quick to take advantage of his distraction, pulling herself free and slamming him to the ground. 

“What the hell were you thinking? Now she's out there alone!” she snarled, missing the way Alphys’s eyes widened in fear and surprise, taking half a step back before aiming the device at something off-camera. “You're not h-him, are y-you?” she asked, and Undyne looked up just as she pushed a button, causing a concentrated stream of light to hit whatever was there. 

A moment later, the light was gone, but Alphys still looked terrified. “N-no! You h-have to be the anomaly! W-why are you k-killing so many m-monsters if you're not them?”

A voice, oddly familiar but far too dark and gruff, echoed from off-screen. “Because, scientist. I enjoy causing pain”

Then, an attack in the shape of a bone, guided by red magic, erupted from the ground and impaled Alphys through the place where her soul sat. 

Undyne went completely slack in surprise and horror, letting go of Sans completely. He made no move to escape, however, for he was also watching in horror as Alphys slowly turned to dust. 

“That’s...that’s the first time I've seen her die” he murmured, but Undyne didn't even stop to consider the oddity of that statement. 

She scrambled to her feet, running for the monitor controls. She couldn't think about it, she couldn't think about the fact that the two people she loved most in the world, the only two people who truly understood her, they were both--

She panned the camera, intent on finding the identity of this murderer. Then she stopped. She heard Sans take a sharp breath behind her, and she stumbled back a few steps in surprise. 

There, dressed in black armor, with an exposed spine, a cracked eye socket, and pointed teeth, stood…

Papyrus. 

 

**Notes for the Chapter:**

> Some people forgot this was a multiverse story, didn't they?


	3. Memory Modifier

**Summary for the Chapter:**

> Okay, this will probably sound super conceited, but I love this story so much. It's like...I've had this great idea and now I'm scared all the time that my writing skills (or lack of) aren't going to do it justice. I hope you guys like this one, I had a little bit of a harder time with it. But soon we'll be getting into the good stuff!
> 
> Warnings: Suicidal Ideation (Mention)

**Notes for the Chapter:**

> I wrote a thing in my OSC, go check it out after you've read this chapter! 
> 
> http://archiveofourown.org/works/8585845/chapters/20790133

Undyne couldn’t help but clutch at the scarf wrapped around her neck. Papyrus was gone. She knew that. She had seen his dust with her own eyes. 

And yet there he stood, dressed in black and red and covered in more scars than Papyrus had even been in fights. He was smiling, but it wasn’t making it all the way to his eyes. He reached down into the pile of dust at his feet and retrieved the machine Alphys had been carrying. He looked it over for a moment, then suddenly, his voice came out of the machine, causing Undyne to jump back in surprise. “SANS!” 

His voice was too deep, too growling. There was an oddly familiar piece of Papyrus in it, yes, but it could never be mistaken for his voice. Once Undyne processed what he had said, however, all of those thoughts were forgotten. 

She turned to her companion in confusion, but he looked as surprised as she was. He made eye contact with her for a moment, seeming to weigh his options, then he stepped up beside her to look at the monitor. She regarded him for a moment, ignoring the screen until another voice joined the first.

“Yeah, Boss?” She looked up to find the owner of the voice very suddenly standing next to this murderous version of her friend. He looked like Sans in the same way the other looked like Papyrus. He was covered in scars, and one of his teeth was gold. He was dressed in black shorts much like Sans’s, but his shirt was red and he wore a leather, fur-lined jacket in place of a blue hoodie. He was looking at the pile of dust instead of the person he was addressing, and Undyne almost thought she saw a flash of revulsion pass through his face. 

“What the hell is this?” Boss asked, shoving the machine into his hands. 

The other Sans took it, turning it around and fiddling with the buttons. “Oh!” He said suddenly. “It's a DT Harnesser” His voice was a lot like the Sans standing beside her, if Sans had made a habit out of smoking instead of drinking. 

“That doesn't tell me anything” Boss spat, and the other Sans flinched as though he expected to be hit. 

“Well, we don't need to talk about it here in the open, Boss. Come on, let's get to camp” he said quickly, pocketing the device and reaching out for the other’s arm, stopping slightly short as though waiting for permission to touch. Boss obliged, placing his arm into his reaching hand, and as suddenly as the other Sans had appeared, they were gone. 

Undyne stared at the empty spot where they had been for a split second, then cursed and scrabbled at the controls. She panned the camera around the entire area, but they were nowhere to be found. 

“What the hell was that?” She screamed at the monitor, resisting the urge to smash something.

Sans hadn't moved since he'd stepped up to look more closely at the monitor. He had his hands shoved forcefully into his pockets as we watched her search fruitlessly. 

“You're not going to find them” he finally said, and she turned to face him angrily. 

“What, does it  _ not matter _ if I find them or something? I didn't ask for your input!”

“This other version of me must be able to take shortcuts, too” he said calmly, ignoring her anger. 

She looked at him again, grinding her teeth, something that didn't work particularly well when you had fangs. “Fine” she said “I'll bite. What does that mean?”

Instead of answering, he disappeared, much like the other two had. His voice rang out from behind her, and she spun to face him, shocked. “That’s what that means” he said, then he was beside her again. 

It was like she'd blinked, but she knew she hadn't. He had just...transported. Apparently he was even more skilled than she’d thought. 

“Okay. I see. So how can we find them?” she asked, making a conscious decision not to think too hard about what she'd just seen. 

“As far as I know, you can't. Shortcuts leave no trace, and it seems to me that they're going to be too well-hidden to find in a more conventional way if they're having to shortcut to it”

“Well then what the hell are we going to do?”

At that, Sans looked down at the place where his hands rested on the table that held the monitor. Undyne was surprised to see his bodily magic spark and tears form, falling softly onto his carpals and staining them blue. “I don’t know” he said simply, his voice breaking on the last word. 

Undyne was beyond shocked. She had never seen Sans cry. Not even when his father--

She pushed the thought away and laid a hand on his shoulder. He flinched slightly, but didn’t make any move to shove her off, so she stayed where she was. 

“I-I’m sorry” he said, wiping hastily at his face. “I don’t know where that came from, I just...this could mean some seriously bad things. You...you have no way of knowing how bad”

She just looked at him for a moment before speaking. “Well, then, asshole. Maybe it’s about time you told me”

 

X-X-X-X

 

Undyne eyed the little device warily. “Sans, are you sure about this?” she asked, for about the hundredth time. 

“Nah, I’m never sure of anything when I’m wasted”

She glared at him, not entirely sure he was joking, and he chuckled darkly. “Just for the record, I am sober at the moment”

Despite herself, she felt her body relax slightly in relief.

“Well, mostly”

“Oh my god, shut the fuck up and just do it already”

She still couldn’t quite believe everything she’d been told, but she figured that with the things she had seen already today, she should really just accept it. 

According to Sans, they were stuck in a sort of time loop, caused by an anomaly in the form of a human child. He’d said that they “reset” the timeline every few weeks, killing all different combinations of monsters, sometimes killing no one at all and actually taking all of monsterkind up to the surface to live happily for a few days before starting all over again, and sometimes hunting down and killing every single monster in the underground. 

For what equated to years, Sans had been forced to endure this alone, telling no one, living the same stretch of time over and over again with no way to stop it, no way to predict who would survive and who would not. 

When he’d told her about the times Papyrus had been murdered for his kindness, offering encouragement and telling the human how much  _ better _ they could be even as his body turned to dust, she had offered him the scarf back. She’d seen him die once, and Sans had been forced to see it, find his dust, thousands of times. She thought he deserved it far more than she did, but he’d only shaken his head. “I was serious when I said to keep it, Undyne. I’ve worn that scarf far too many times, and it’s always ended with...well…” and he’d rubbed at his sternum through his shirt absently, refusing to tell her exactly what had happened. 

He’d continued with the narrative a bit more quietly after that, telling her how he’d started drinking every reset because, as he said with the most mirthless laugh she’d ever heard, he couldn’t even kill himself properly, he’d just come back next reset. So he’d needed an escape. In one of the resets, apparently, he’d drunk a little too much and ended up in the labs. He didn’t say why he had gone there, but Undyne was fairly certain that she knew. 

He said Alphys had found him, and he’d let everything out. Every reset, every death, all of his pain, came spilling out amidst sobs and pleas to just leave him alone to stop feeling it all.

Then, he’d said, the most amazing thing had happened. Alphys had told him that she remembered it all, too. She remembered all of her resets.  _ Everything _ . And until that moment, she had thought she was alone as well.

Undyne had been confused about this. Knowing what she did about Sans’s history, it made sense for him to remember, but... “How did Alphys know all of it? She wasn’t--” Sans had shaken his head, cutting her off. He explained about a machine implanted in her soul when she had been working under Gaster, an illegal experiment towards the end of his life that Alphys had, to say the least, not agreed to. A machine that was called a “memory modifier” that allowed her soul to react with disruptions in a timeline and retrieve past memories. 

This was why Undyne was here, sitting on a hospital bed, about to be operated on by someone who she was pretty sure hadn’t had any real scientific experience since he was about 9 years old (No matter how good he had been at the time).

“This is a terrible idea” she said as Sans picked up some sort of sharp-looking medical instrument and pretended to give it a spit-shine.

He laughed and nodded. “Oh, yeah. But hey, never in my several hundred years of living have either of us ever had a good idea. We've always needed the other two for that”

She shuddered a little at that. As Sans had related the events of his life to her, she had found her opinion of him changing. Yes, he could be a useless asshole a lot of the time, but she couldn’t imagine living for as long as he had, through so much pain, remembering every single bit of it. It was half of the reason why she had insisted on this. Although she now realized that he was probably the strongest person she had ever met, she also recognized that he was on the end of his wire. He needed someone else here, during this. He needed someone who understood to help him figure out what was going on. And, hell, even once it reset again, perhaps she could help Alphys and Sans figure out a way to stop all of this. 

Undyne couldn’t help the swell of hope that accompanied thoughts of Alphys and Papyrus. She would see them again, it would all reset, and she would see them again. It was like they weren’t even dead! The practical part of her said that she shouldn’t hope too hard, just in case, but screw that.

She was brought back to reality by Sans picking up the device and approaching her cautiously. “Sorry about the whole no-sedative thing” he said, grimacing. She just snorted. It was a common-known fact that operating on someone’s soul while they were under a sedative was incredibly dangerous, and, more often than not, ended in that person falling down and subsequently turning to dust.

She braced herself against the bed, the back of which had been raised so that she could sit comfortably. Sans cursed under his breath suddenly, and Undyne made a face. He couldn’t possibly have fucked up already, could he? He hadn’t even touched her yet. 

“What’s wrong?” she snapped, more nervous than she would ever let show. 

“I don’t wear belts, I don’t have anything for you to bite down on”

She just crooked an eyebrow at him for a moment, trying not to be concerned that this was going to be painful enough that she would need something to bite down on. Instead, looking him in the eye, she very deliberately unhooked her own belt, which was in clear view since her shirt was just a black tank top that she knew was on the tight side, and pulled it from around her waist. “You mean a belt like this one right in front of you?” she asked snidely.

“Oh, fuck off. I’m nervous, okay? Bite down on it so I can get to the whole ‘causing you pain’ thing”

In response, she just showed off her multitasking skills by folding the belt and flipping him off at the same time. 

She stuck it between her fangs and bit down, then leaned back and closed her eyes, attempting to breathe calmly. 

She felt her soul be summoned, and she couldn’t help the sweat that started to run down her face. She felt Sans grab it from the air, much more gently than she would have expected, then she heard him take a deep breath. Then he started the incision. 

Undyne was suddenly very grateful for the belt between her teeth as she clenched her jaw, her choked-off scream turning into a prolonged groan instead as her eyes flew open and she gripped at the sides of the bed hard enough to cause the metal to bend slightly. It felt as though the cut was being made on every part of her body at the same time, the pain lancing through her in a way that, despite being captain of the Royal Guard and thus having been in her fair share of fights to the death, she had never felt the likes of before. 

Then he was done with the cut, and she felt relief the likes of which she had never felt before. The pain almost immediately died down from a sharp burn to a hard throb as Sans poured just enough green healing magic into her so that the cut didn’t seal. Then, with a quickness and precision she hadn’t known he possessed, he picked up the memory modifier from the table and inserted it into her soul. 

She fidgeted at the unfamiliar sensation of having something put inside the very essence of her being, then sighed aloud as he finished healing her and returned the soul to her chest.

“That went well!” he chirped.

Undyne, still sweating heavily, chest heaving and gasping breaths making their way out from her lungs, gave him the look she usually reserved for idiotic teenagers who were attempting to talk back. She wanted, more than anything else in the world right now, to flip him off again, but she couldn’t seem to get her hands to release from their cramped position. 

He put away the tool he had used and picked up the paper they had found describing how to use the memory modifier. 

“Okay” he said “Now you have to concentrate on it and sort of will it to work”

She sighed deeply, finally convincing her fingers to loosen and removing the belt from her mouth. “Yeah, that’s real descriptive, asshole” she choked out, her voice seeming scratchier than normal. 

“Shut up and concentrate, Undies”

“Do not fucking call me that, ‘Sansy Pansy’”

“Shut your--” his voice seemed a few octaves higher than normal, and he stopped to clear his throat decisively. She snickered and he frowned. “Just concentrate” he said, his voice back to normal. 

She let her eyes fall closed. “Concentrate”? What the hell was that supposed to mean? She turned her thoughts to her soul, attempting to find and control the foreign object she could feel there. Nothing happened for several long moments, and her eyes opened so she could glare at Sans. 

He wasn't looking at her anymore. Instead, he was entirely focused on the portable version of the monitors upstairs. She could see him flicking between cameras, panning the areas they covered and moving to the next one with a level of concentration she hadn't seen from him since they were just kids and he was trying to teach himself theoretical calculus. 

Sans had said, earlier, that the arrival of these strange copies, and especially the fact that they now had possession of the DT Harnesser, could mean some serious trouble. Apparently, the machine was used to harness whatever power the anomaly carried and use it to do anything the child itself was capable of, effectively stripping the human’s power from them and containing it within the device. With that power, these new arrivals could do anything they wanted. They would have all the time in the world, and nothing could stop them. Everything was depending on finding them, but if the kid reset now and Undyne forgot everything she had learned, she would have no idea they were here and she would be entirely helpless to stop them from starting to kill their way through the underground all over again. 

Undyne closed her eyes again. She had to figure this out, and quickly. 

She concentrated again, this time focusing, instead of on the device implanted in her soul, on where she thought the memories themselves might be. In doing so, she very quickly discovered a barrier that she had not been aware of until that moment. She prodded at it lightly, almost curious, then, as she tended to do with all things, drove straight into it with all of her might. 

To her surprise, she felt the memory modifier click, sending a shuddering sensation through her whole body. Then the barrier smashed, and suddenly, her body locked up. 

She clenched her fingers back into the deep dents she had already bent into the sides of the bed, and her teeth clenched together hard enough to make her wish that the belt was still between them. 

_ “Understand, human? This is your only chance at redemption. Give me your soul, Or I’ll tear it from your body!” _

It wasn’t that it hurt, really. It was more the memory of hurt, of  _ being _ hurt, over and over and over again…

_ “Undyne! Y-you’re hurt!” _

_ “Hurt? It’s nothing. Next time, listen when I tell you to leave, okay?” _

_ “Undyne, I…” _

_ “I’ll take care of this. Get out of here! _

_ “Heh…’it’s nothing’...No...s-somehow, with just one hit...I’m already...already…D-Damn it! Papyrus...Alphys...ASGORE...Just like that, I...I’ve failed you.” _

The memory of turning to dust so many times...it was not pain, it was something...other. Something unpleasant. All of the memories she had, coming back at once, hundreds of years worth of death catching up to her…

_ “So why are you here? To rub your victory in my face? To humiliate me even further? IS THAT IT? _

And so many times, sitting across a table from someone she didn’t know was a murderer, someone that, she supposed, hadn’t been a murderer that time.

_ Damn it...So even THAT power...It wasn’t enough…? Heh...heheheh...If you think I’m gonna give up hope, you’re wrong. ‘Cause I’ve got my friends behind me. _

Everything was starting to hit her all at once, the memories becoming overwhelming, too many at once to be able to pick anything out, flashes of the memories coming across her vision.

_ And we all have one goal...To defeat YOU! _

She could feel her body shaking against something cold and hard, which conflicted with hundreds of sensations that all seemed to run across her at once.

_ I can’t believe he leapt through the window like that. Normally he NAILS the landing. _

Somewhere off in the distance, she could feel someone shaking her, saying her name in a voice that sounded vaguely panicked. 

_ You’re gonna have to try a little harder than THAT. _

She realized her throat hurt. Was she screaming? Or was it the person saying her name? Who was saying her name?

_ The heroine appears. _

Sans. That was Sans calling her name. Why was Sans calling her name? Her mind strained for an answer to the question, pulling away from the rapid stream of memories. 

Suddenly, everything stopped. 

_ “Heya Sparks” _

_ She turned towards the speaker, making a face before it broke into a smile. “I thought I told you not to call me that” _

_ Sans sat beside her on the couch, bringing the smell of cinnamon and butterscotch along with him, like he always did these days. “Yeah, but you should know by now that I never listen” _

_ “It doesn't even make sense, I’m a fish monster, not a fire elemental or a pyrope. Why don't you call Grillby Sparks?” _

_ “Because he's not the one with the fairly explosive personality” _

_ “Oh, shut up. I'm calling you lazyass then” _

_ “You do that anyway” _

_ She snorted and half-turned her attention back to the TV. The stuff here on the surface was about a million times better than the never-ending MTT reruns they'd had back in the Underground. Not that she would ever actually tell her fiancée’s best friend that. No one needed that stupid robot’s head getting any bigger.  _

_ “How're the wedding plans going?” Sans asked, stretching slightly.  _

_ “I honestly have no idea. Alphys has been handling all of it. I told her that as long as there will be a red velvet cake and I get to wear a pretty dress, I don't much care what happens” _

_ “I didn't much take you for the dress-wearin’ type” _

_ “What can I say, there's just something about how powerful they make you feel” _

_ “You can't even properly run away in a dress” _

_ “Hah! As if I would ever run away from a fight!” _

_ He just laughed, leaning forward and propping his chin in his hands. She looked at him for a moment, taking in his hooded eyes and twitching fingers.  _

_ “Are you okay?” She asked, concerned for her friend.  _

_ “Yeah, yeah. Don't worry about it” _

_ She frowned, then reached for the remote and turned off the TV, giving him her full attention.  _

_ “Sans, don't do that. You promised you'd always come to me if you ever started to--” _

_ He sat up fully, putting his hands up in front of him in a placating sort of pose. “No, it's nothing like that! I've been a lot better since...since that happened. It was nice to get some help, finally.” _

_ “I'm sorry, Sans” _

_ “For what, suplexing me? I already told you that was okay, a little force was probably necessary to get me to--” _

_ “No, not for the suplexing, I definitely don't feel sorry about that” she said, grinning. “I'm sorry that you had to feel so alone for such a long time” _

_ He was quiet for a moment. She just watched him as he fiddled with the hem of his shirt, seemingly searching for something to say. “You know…” he started. “Between you, Papyrus, and Tori, I don't think I'll ever have to feel alone again. I...I can't thank you enough for that” _

_ “You're welcome, lazyass” _

_ “Aw, come on, Sparks, you ruined it! We were having a moment!” _

_ The sound of their shared laughter filled the room, lightening them both to a degree neither of them had realized they needed.  _

Undyne’s eyes opened slowly, and she heard Sans breath a sigh of relief. “Thank god. I didn't know it was going to do that. Do… do you remember it all now?”

He looked like he had then, she realized. Tired, and scared, but with hope in his eyes, hope like she now realized she hadn't seen since that particular reset so long ago. 

“We were all so happy, once. We...we all found forgiveness for the things we’d done” she said, her voice breaking slightly. 

He just looked at her for a moment, confused, then he seemed to realize what she was talking about and pain filled his eyes. “Yeah” he said in a whisper. “I guess we all kinda were, weren't we?”

**Notes for the Chapter:**

> I'm sure you've noticed by now that ive been messing around a bit with the undertale world. In truth, I'm just kind of shifting around stuff for the sake of the story, but I guess we can call it a new AU if you guys want? (There's definitely not enough AUs yet, right?)  
> To clear up any confusion, in this one, some of the more major changes are that Undyne and Alphys were already dating when frisk fell down here, and everyone remembers gaster because he killedhimself in a way that didn't involve falling into the core. Also the whole thing where Sans is a bit more of an asshole than usual.


	4. Wow look we're barely a team!

**Summary for the Chapter:**

> Warnings:Wow more death this is off to a great start
> 
> Dialogue in the beginning is taken directly from the AfterTale comic by loverofpiggies (with some creative liscence taken) but just a reminder, this is not AfterTale nor will it have really anything to do with that, I just really liked the way they portrayed this opening scene, and I, personally, consider it the closest thing we have for canon for how this would have gone down.. [http://loverofpiggies.tumblr.com/tagged/Atpt1/chrono]
> 
> This chapter gave me so much shit. I'm so sorry if it sucks. But hey, now we can FINALLY get to the actual stuff that I wrote this story for!

_ When Undyne arrived at the Royal Labs, she was completely out of breath. She had run the entire way from her home in waterfall, and even with her seemingly unending supply of stubbornness, even she couldn’t call the exhaustion a nerd and kick it out of her shaking muscles. _

_ She pounded on the doors, and they slid open immediately. She stormed through, trying not to show how tired she was.  _

_ She was met almost immediately by Alphys, who had tears streaming down her face and was being even more quiet than usual. Undyne immediately crouched and wrapped her up in a hug, trying her best not to cry alongside her. She couldn’t afford to break down now. She needed to be strong, not only for Alphys, but for the entire underground.  _

_ “Where are they now?” she asked once Alphys let her go, standing and striding over to the monitors. _

_ “They’re almost to Temmie Village” Alphys murmured, casting a quick glance at the other person in the room. Undyne followed her gaze, and when she saw Sans, it was all she could do to keep her face from crumpling. _

_ He was hunched over in a chair in a corner, unmoving, with Papyrus’s scarf clutched tightly in his hands, pressing the red cloth to his face. He wasn’t making a single sound, not a sob or a cry or anything at all.  _

_ As Undyne watched him, she knew exactly the kind of numbness that was weighing him down. It was weighing her down, too.  _

_ Undyne took a deep breath, then turned to Alphys and said, “Well, wish me luck. I can probably catch up to the human before they leave waterfall. _

_ Alphys’s voice grew panicked. “N-no...Undyne, you  _ can’t!  _ That human...No- that  _ thing _! It can’t be stopped!” _

_ When Undyne didn’t reply, Alphys continued. “You saw what it did to P--” she cut off abruptly and shot a guilty look towards Sans. “I mean, what it’s been doing to everyone!” She grasped Undyne’s hands, and undyne couldn’t look her in the eye for a moment. “We need to escape! We  _ have  _ to evacuate!” _

_ It was a long moment before Undyne said “No. I can’t, Alphys” She steeled  herself, then made herself look Alphys in the face. “But you...you have to prepare. Prepare for the evacuation…” she took a deep breath. “But you know I have to fight” _

_ Sudden horrified realization crossed Alphys’s face, and then it crumpled and she looked to be fighting back more tears. “Undyne...did you come here...because…” _

_ “-because I think I’m going to die? HA! Never! I’ll kill it!” Undyne cut her off, pounding one fist into the other palm and grinning at her with confidence. “Just, prepare for the worst, and hope for the best.” _

_ Alphys began to cry for real, and Undyne stood back up and kept her smile on her face, despite the fear and sadness roiling in her soul. “I can feel the whole world chanting for me. I can’t lose! So don’t cry, Alphys!”  _

_ She leaned down and hugged her again, then stood back up straight. She was about to leave when she found her gaze drawn to Sans again. He still hadn’t moved, and she felt the false bravado slip from her face.  _

_ She made her way to him, hesitating for a moment before placing a hand on his shoulder. “...Sans...I-” _

_ As soon as she touched him, he shoved her away from him, hard, and she thought she saw a spark of his blue magic for a moment before he turned to face her. _

_ Her immediate reaction was one of anger, but she felt Alphys’s panicked hands grabbing onto her arm, keeping her from immediately punching Sans in the face. _

_ “Oh, hey Undyne.” she heard him say, and she looked up to see him smiling at her as though he wasn’t still clutching onto the scarf like a lifeline.  _

_ “Sorry about that. You scared the  _ carp _ outta me.” _

_ She made a face at him for a moment, then found a smile curving her lips despite herself. “...heh. Right. That’s just how you are.” She said, folding her arms.  _

_ Then she took another deep breath and turned quickly, kissing the top of Alphys’s head and beginning to make her way to the lab doors. “I have to go. I can’t waste any more time.” _

_ “U-Undyne…” _

_ “Don’t worry, Alph” she said, grinning back at her again. Behind Alphys, Sans stood slowly, still holding the scarf tightly. “I’m going to fix everything. Just believe in me, okay?” _

_ Alphys just looked at her for a moment, sadness evident in her eyes, before she nodded. “Okay…” _

_ Undyne finished crossing the room, then, before the doors opened, she stopped.  _

_ “And, uh. Sans.” she couldn’t seem to make herself look at him. “...I...I loved him too.” _

_ Then she opened the door, stepping through and beginning to run in the direction of waterfall. _

 

Undyne groaned and grasped at the place in her chest where her soul was hidden. 

“More memories comin’ in?”

She looked up at Sans, who was using the cameras to search for his and Papyrus’s alternates again. They had moved up onto the main floor of the Royal Labs after the insertion so that they could track them down and stop them, but Undyne hadn’t been able to stand in front of the monitor for any length of time, so she was sitting in the same chair Sans had been sitting in in the memory. 

Undyne cleared her suddenly dry throat and croaked, “Yeah. I-I think that was the first one where the k-kid started killing people”

Sans turned away from the cameras to look at her, then after a moment he turned back and said, “That one was...hard”

They had fallen into a pattern. The flood of new memories hadn’t stopped after the initial flow, and so every time one came into her mind, she would tell him about it and he would give her a bit of perspective on it, since she still didn’t have all of the pieces. It would have been hard to make any sense of what she was seeing if she didn’t have Sans telling her how it all fit together.

“The kid had reset a couple of times before that, but they had always brought us up to the surface.” he continued monotonously “Then...then they started killing people, out of nowhere, and I’d thought they liked all of us, y’know? So I thought, maybe there’s a reason? Maybe they were being forced into this? But then…”

“They killed Papyrus” Undyne said quietly. 

Sans just nodded, then moved to the next camera, panning quickly. He was about to move to the next one when Undyne said “Hey, wait! Look, back behind those trees there”

She stood and moved to the screen as he zoomed in, looking carefully. “There’s definitely  _ someone _ but...I can’t quite…” he growled in frustration.

“Is there another camera closer to them?”

“How should I know? I don’t exactly have a fuckin’ map of the area, Undies”

She sighed in consternation, then took the controls, mumbling ‘sansy-pansy’ under her breath as she blipped to the next camera in the lineup.

There, in perfect, crisp view, there were three figures that both of them knew far too well.

Boss was holding the DT Harnesser, and seemed to be leading the others. The other Sans trailed behind the other two, tripping over the occasional root that didn’t seem to affect the others at all.

However, it was the third member of the party that had Undyne staring at the screen with her mouth open.

It was her in the same way the other two were the skeleton brothers. This Undyne was nearly the other Papyrus’s height, and instead of the heavy armor that Undyne usually would be dressed in for work or the black tank top and jeans she would wear casually, this version of her was dressed in ripped black jeans, tall red boots, black gloves, and a black cropped breastplate with a red image of a broken soul. Her red hair was worn in the same way Undyne wore her own, but it’s cut was choppier and the ends looked slightly burned, as though she had been giving herself haircuts with her own magic spears.

They kept walking, not talking, until they were out of reach of the camera they were on, and as soon as they were out of sight, Undyne jumped to the next camera, following them as they walked through the forest. 

Suddenly, beside her, Sans gasped. “They’re going to the ruins” he said. “Shit, they’re going to the ruins, we need to go  _ now _ .”

And with that, he grabbed her arm, and she felt the world warp around her. Suddenly, she landed face-first into the snow, dragging Sans down with her. He landed where his stomach would be if he wasn’t a skeleton, and despite the fact that there was nothing but air, he seemed to get the wind knocked out of him. As she pushed him off her and stood shakily, she found herself wondering, not for the first time, how exactly skeletons’ bodies worked. 

Sans stood up next to her, and quickly dragged her behind some trees. 

Wait, trees?

Undyne looked around her and found that they were hidden beside the path that led to the Ruins door. “Fuck, Sans, was that a shortcut?”

He nodded tersely, looking around the trees they were hidden behind.

“Please tell me the next time you decide to just fuckin’ grab me and--”

He slapped a hand over her mouth, and when she went to grab it and push it away, a loud curse on the tip of her tongue, he hissed “Shut the fuck up” and gestured towards the path with his free hand.  

The other Sans had emerged from the forest and was standing casually by the ruins doors. His hands were shoved deep in his jacket’s pockets, and his eyes were hooded, as though he were on the edge of falling asleep. However, Undyne hadn’t become captain of the Royal Guard for nothing, and she could see his alertness in the brightness of his eyelights and the way his bones could be heard rattling if you were listening quietly enough. The other two were nowhere to be found at first, but after looking into the forest, Undyne caught a flash of movement here and there that signalled they were moving along the opposite side of the path from her and Sans, in the direction of the bridge.

Sans seemed to have caught on to the same things she had, because he was deathly calm. He was looking very intensely in the direction of the other Sans, as though he was trying to see what was going on with him. 

Undyne went to tap him on the shoulder, to point out the location of the others, when the door to the ruins began creaking open. She jerked her gaze up, trying to see the child, just in time to see the other Sans fade into the trees. 

The kid stepped out of the ruins confidently, shutting the door firmly behind them. They wore a striped sweater, and their brown hair was about chin-length. They started walking purposefully down the path, and Undyne saw Sans’s alternate step out of the trees, following them quietly. 

Undyne and Sans trailed them cautiously, Sans muttering under his breath in a strange language that Undyne knew he slipped into when he got upset. She couldn’t understand what he was saying, but based off the tone, she was fairly sure it was a lot of swearing. 

They didn’t know what these assholes had planned, but they knew it wasn’t anything good. They needed to get that DT Harnesser before--

_ “Oh, I’m sorry, Miss Captain of the Royal Guard!” Sans was standing in front of her, and he was giving her what was probably the most sarcastic salute she had ever seen. “Did you want me to kill another kid or something? Because guess what? I fucking can’t!” _

_ “What the hell are you talking about, Sans?” she heard her own voice shout back. “What is wrong with you lately?” _

No, no, not right now, she couldn’t blank out now! Undyne wrenched herself back into the present, catching herself before she stumbled facefirst into a tree. She looked desperately at Sans, trying to think of a way to warn him without giving them away, but he was entirely focused on the human and his alternate, already leaving her behind as her kept up with them. 

Undyne looked at the path just in time to see the other Sans stomp down on a branch with all his might, breaking it in half and causing a loud  _ snap! _ The human didn’t even pause, but Undyne thought she saw a hint of a smile on the little creep’s face.

That’s right, Sans had told her about how he always followed the human to the bridge, stepping on the branch and then holding out a hand for a handshake. It was how he judged what the human had done while they were in the--

_ “I’m talking about how I’ve tried and I’ve tried and I can’t kill them! They have all the time in the world, Undyne!” Sans started to laugh, a dry, humorless affair that left her sad and angry all at the same time. _

_ “Sans, come on. We don’t have time for you to act like this! Just tell me what’s wrong so we can get past it and you can do your damn job!” _

Undyne pulled herself out of the memory again, but this time it was harder, it seemed like it didn’t want to give her up until it was over. She hurried after Sans, still trying to be quiet, and she caught up to him just as the human reached the bridge. The darker Sans raised a hand and froze the human in their tracks.

“Where is the Harnesser?” she heard Sans murmur. “We can’t let them use it, Undyne, we have to get it back or the Underground is as good as gone”

_ “The Underground is as good as gone! And I can’t do a damn thing about it, no matter how many times you come here and tell me to!” _

“Sans--” she started, but he silenced her with a gesture and pointed at the others.

The other Sans was laughing. “You know, sweetheart, I’d tell you to turn around, but I don’t think that’s even necessary for you to know that you’re in some deep shit” he growled.

_ “Sans, I--” _

_ “We were friends once, you know.” he was almost whispering now. “We all made it to the surface, resolved all our shit. We all found forgiveness for the things we had done” _

The kid looked terrified now, trying to turn around to look for the half-familiar voice. “Who are you?” they asked, trembling.

Undyne almost felt sorry for them. 

Almost. 

The alternate pulled one hand out of his pocket, raising his arm out to the side and giving a quick jerk towards the sky. The human was jerked up into the air by their soul, hanging limply as they seemed to give up, awaiting whatever was coming for them.

_ “I don’t know what the hell you’re talking about, but I’ve had enough!” Undyne stepped forward and grabbed him by the front of his shirt, pulling him up to her eye level. “Monsters are dying, Sans! We need your help to get through this!” _

The other pulled his other hand out of his pocket, and held tightly in it was the DT Harnesser. Sans made a small noise and started to step from the trees, but he was beaten to it by the other Undyne and Boss. 

“C’mon, Red. Wreck ‘em” snarled the fish lady. 

Undyne felt a peculiar sensation, as though the world was about to fall out from under her feet, then she heard Boss say, “Don’t you dare reset, human. We will find you each and every time”

_ “Each and every time, you do this” Sans said, going limp in her grip. “You come here, fire under your ass, ask for my help. You have no idea how much it just doesn’t matter” _

The feeling stopped, and Undyne realized Sans had frozen beside her, watching as his alternate pushed a button on the device.

The human  _ screamed _ . Their soul manifested in front of them, bright blue from the hold, and began to crumble. As it fell apart, the human flailed, trying to escape. As the soul turned to dust, something began to flow from it to the device held in Red’s hand. Undyne could feel that same sensation, starting and disappearing over and over again, and she realized the human was trying to reset and failing. When the soul had disappeared, the hold on the human’s body seemed to disappear, and they fell to the ground, lifeless. 

Undyne stared in shock at the small body. Despite everything she now remembered them doing, despite all the pain and suffering they had caused...it was just a child. She remembered so many times, before they started killing anyone, that they had sat at her table, drinking tea, becoming ‘besties’. 

In spite of herself, she felt silent tears begin to fall. 

“No…” she heard Sans say in a whisper from beside her. “It didn’t reset...They didn’t reset…” he was getting steadily louder, and she reached out to try and silence him--

_ “Sans, seriously! If this is a human, they could kill everyone! If you don’t stop them, they could kill--”  _

_ She was cut off by another dry laugh. “Papyrus, right? You were going to say Papyrus?” he was looking her right in the face, his eyelights dim. “It doesn’t matter, Undyne. It really doesn’t. He’ll always come back.” _

It was like Undyne had just closed her eyes, and when she opened them, Sans was out on the path, running at the other group much faster than she’d thought he was capable. 

“Shit!” she swore under her breath, ducking under a branch and following after him as he seized  Boss and Red by the souls and slammed them both against nearby trees. Red kept a tight hold on the DT Harnesser, however, and bared his sharp teeth at the other, growling. “I knew you had to be around here somewhere, asshole” he said. Sans seemed to be completely unaware of Undyne’s alternate coming up behind him, and didn’t even turn when Undyne summoned a spear of her own and used it to deflect the one about to hit him. The other Undyne turned to her with a hiss, summoning more spears and throwing them at her. Undyne dodged around them, summoning her own, and leapt at her alternate, a scream of fury piercing the air. 

The  _ clang _ of their spears meeting seemed to finally jar Sans from his rage, and he turned to look at them for a split second. 

Red immediately took advantage of the distraction and freed himself from Sans’s hold with a  _ ping _ , immediately tossing the DT Harnesser to Boss. He summoned several long bones in the air, throwing them at Sans just as he turned back to the other.

Undyne lost track of them for a moment as she dodged an attempt to turn her soul green, and she swung again.

_ “What the hell is wrong with you?”  _

“No! Stop!” she shouted aloud, gripping onto the side of her head as she stumbled slightly, allowing the other to push her onto the ground.

_ “Why can’t you just do your god-damned job and stop being such a lazy asshole?” _

“Begging for mercy already?” the other sneered, holding a spear to her throat. “This universe must breed monsters even weaker than I originally thought”

Undyne tried to dislodge the spear, but was rewarded with a burn to her hand. She heard a cry that must have come from Sans, and a thump from the direction of the tree Boss had been pinned to that must have signalled that he was free.

_ Sans’s laughter was filling the air, and there was even less joy in it than before. _

Boss appeared in front of her, confirming her suspicions. “Take them alive. They could be useful” he snarled, and the other Undyne grinned and summoned another spear, raising it into the air before bringing it down hard on Undyne’s head.

_ “Aw, c’mon, Sparks. I’ve always been lazy. You know that. The difference is that I just don’t care anymore. And you know why, somewhere in there. You just can’t remember.” _

Everything went dark.

**Notes for the Chapter:**

> In case this isn't clear, anything in italics is a memory, and the normal stuff is what's happening right now.
> 
> Also, if I ever get motivated to, I might come back and expand that fight scene. Also, that picture is what inspired me to write this story. Just sayin' (credit to sl4ughtermelon on DV)

**Author's Note:**

> I'm not going to be finishing this story, feel free to pick up where I left off and link me so I can read it!


End file.
